Rotary piston internal combustion engines require fewer parts than reciprocating piston engines. However, to achieve complete circular rotary piston movement, it has been necessary to provide reaction plates that were moved in and out of a toroidal cylinder to provide a reaction for expanding combustion gases to provide a force for moving the piston and allow the piston to pass. Such engines are difficult to manufacture and are not common.
Many so-called “rotary” piston engines are engines where the pistons reciprocate over a part of a circle and do not rotate through a full circular arc.
Among the best known prior art Otto cycle internal combustion engine with a continuously orbiting and rotating piston is known as the Wankel engine. The concept was known for many years, but the Wankel engine was first operated successfully by Felix Wankel. A Wankel engine is shown in U.S. Pat. No. 2,988,008 issued Jun. 13, 1961 to F. Wankel (“the Wankel patent”). The Wankel patent relates to an engine having a peritrochoidal housing where the inner surface of the housing encloses and provides support and guidance for a generally triangular piston in an eccentric orbit. During orbiting of the piston, the piston center describes a circular orbit about the center of rotation of an output shaft. The eccentric motion of the center of the piston in relation to the center of rotation of the output shaft is used to drive a crankshaft that generates a circular rotation of the output shaft.
Other types of rotary piston engines are shown in U.S. Pat. Nos. 1,687,511 issued Oct. 16, 1928 to Powell (“the Powell patent”) and 4,076,471 issued Feb. 28, 1978 to McClure (“the McClure patent”). Unlike the Wankel engine, the engines shown in the Powell and McClure patents have pistons that rotate through 360 degrees. The Powell and McClure patents are Otto cycle engines using a gaseous or vaporized liquid fuel with inlet, compression, combustion and exhaust cycles. The Powell and McClure patents require one full rotation of a piston to achieve a full Otto cycle. In the Powell patent, the pistons are supported on a rotating web that is supported for rotation by an output shaft and bearings, and are further supported in a circular toroidal “cylinder”. The pistons in the Powell patent drive an output shaft.
In each of the Powell and McClure patents, a plate or valve extends into the “cylinder” to provide a reaction or “thrust” surface for containing the expanding combustion gases generated during a combustion cycle. The reaction plate surfaces are radial and perpendicular to the “axis” of the toroidal “cylinder” and are inserted in the “cylinder” to provide a reaction for the combustion gases and are removed from the “cylinder” to allow the piston to move in a complete circular path without interference. Other types of rotary engine are described and shown at the internet encyclopedia known as Wikipedia.
The pulse jet engine concept shown and described by Wikipedia is an axial flow rotary engine. In essence, a rotor is rotated in a housing thrust from pulse firing of a jet engine. The rotor is driven by momentum transfer of the jet acting on the rotor. Wikipedia describes a pulse jet engine as:                A very simple form of internal combustion engine based on jet engine principles where combustion occurs in pulses.        
A fuel air mixture and a combustive spark or flame is fed through the rotor to the jet engine. The reaction to expanding and escaping combustion gas jets is used to power the rotor of the engine.
The Wikipedia description of Pulse detonation engines states:
All regular jet engines and most rocket engines operate on the deflagration of fuel, that is, the rapid but subsonic combustion of fuel. The pulse detonation engine (“PDE”) is a concept currently in active development to create a jet engine that operates on the supersonic detonation of fuel.The basic operation of the PDE is similar to that of the pulse jet engine; air is mixed with fuel to create a flammable mixture that is then ignited. The resulting combustion greatly increases the pressure of the mixture to approximately 100 atmospheres (10 MPa), which then expands through a nozzle for thrust. To ensure that the mixture exits to the rear, thereby pushing the aircraft forward, a series of shutters are used to close off the front of the engine. Careful tuning of the inlet ensures the shutters close at the right time to force the air to travel in one direction only through the engine.The main difference between a PDE and a traditional pulsejet is that the mixture does not undergo subsonic combustion but instead, supersonic detonation. In the PDE, the oxygen and fuel combination process is supersonic, effectively an explosion instead of burning.One of the differences between a pulse jet engine and a pulse detonation engine is in the manner in which the fuel air mixture is converted into an expanding gas. A pulse jet engine involves the deflagration or burning of the fuel air mixture whereas a pulse detonation engine uses explosive detonation of the fuel air mixture. Deflagration generates a flame front velocity that is subsonic whereas detonation generates a flame front velocity that is supersonic, i.e., Mach 5. Detonation is a substantially more powerful reaction and results in an extremely rapid type of combustion reaction where the pressure-wave created travels at super-sonic speeds.
The engine of this invention is a rotary piston engine that can use either pulse jet or pulse detonation gases as a source of motive power.
Some prior art engines combine conventional turbine jet engine technology with pulsed jet or pulsed detonation supplementation. Examples of such hybrid jet engines include U.S. Pat. Nos. 6,477,829, 6,666,018, 6,813,878 and 6,883,302. A rotary pulse detonation engine is disclosed in U.S. Pat. No. 4,741,154 issued May 3, 1988 to Eidelman and assigned to the United States of America. Another rotary pulse detonation engine is shown in U.S. Pat. No. 6,725,646 B1 to Callas et al. dated Apr. 27, 2004.
The engine of this invention is intended to operate using principles of pulse detonation, pulse jet combustion or a combination of pulse detonation and pulse jet combustion. The engine operates with a detonation or combustion cycle that includes compression of a fuel air mixture, combustion or detonation of the compressed fuel air mixture, and exhaust of the products of combustion of the fuel air mixture. In the present invention, it is possible to obtain 4 or more Otto cycles in a single revolution of a piston.
The compression of the fuel air mixture is accomplished by conventional means, i.e., a radial turbine compressor, and exhaust of the energy depleted products of combustion is achieved by natural or assisted aspiration.
Ignition of the compressed fuel air mixture is achieved using an electrically powered igniter and suitable electrical and electronic controls.
The engine of this invention may include a cooling system using a circulating fluid coolant.
The engine may also include a starter motor for initiating operation of the engine. The starter motor may, when the engine is operating, also function as a generator for providing electrical energy necessary for maintaining operation of the engine.
It is a primary object of this invention to provide a rotary piston engine that uses pulse jet or pulse detonation energy to move a piston.
Another object of the present invention is to provide a rotary piston engine having a continuous unobstructed circular path of piston travel.
Other objects and advantages of this invention will become obvious from the following detailed description of construction and operation.